Without any definitive evidence of the whereabouts of Malaysia's missing passenger plane, many Chinese families are fostering conspiracy theories.

Devastated relatives of passengers on missing flight MH370 were told today by Malaysia's prime minister that searchers must now assume the plane was "lost" and it had crashed in the Indian Ocean.

The families were called to meetings this morning to be told the fate of flight MH370, which vanished on March 8 with 239 people, including two New Zealanders, aboard on its way from Kuala Lumpur, Malaysia, to Beijing.

"It is, therefore, with deep sadness and regret that I must inform you that according to this new data flight MH370 ended in the southern Indian Ocean."

Families have been booked on chartered flights to Perth.

But many families remain suspicious of the veracity of information from the Malaysian Government, after two weeks of theories, counter-theories and confused information.

"Why won't you tell us the truth, why don't you respect our families?" one young woman asked after the announcement.

Even as the news unfolded today, families across China who have been communicating via group messages on social media application WeChat were talking about protesting at the Malaysian embassy in Beijing and crowd-funding a campaign to uncover the "truth" about flight MH370.

Others had talked of the likelihood that Malaysian authorities were "hiding" the plane.

"They don't want to accept that they're gone, and the only way for them to maintain their sanity while not believing they're gone, is to have a theory that they think makes sense to hold them together," said Paul Yin, a grief counsellor.

"It's not really about believing it, it's about needing it."

Yin said at least some form of finality would enable families to begin the healing process but that Chinese families were taking it particularly hard for cultural reasons.

"In the Chinese culture, when a certain person gets to a certain age your meaning of life is basically all about the younger generation and your legacy," he said.

"With so many elderly couples, sometimes their children and grandchildren are all on board the plane. Potentially it could be confirmed they have no-one left."

But the distrust of information from Malaysian authorities could mean that finality may only arrive though firm evidence found in the intensifying multinational search being co-ordinated by Australia in the Indian Ocean.

Malaysia Airlines indicated it would fly families to Perth at their request if evidence of wreckage was discovered near there. Australian embassy officials in Beijing are understood to have made preparations to fast-track visa applications for this eventuality.

"They say my son is dead," one man told Fairfax Media quietly, his eyes barely leaving the floor as he left the hotel.